In modern chip applications, a circuit often has two or more power supply inputs, and a chip for the circuit can work under any of the power inputs. For example, under normal circumstances, the chip is powered by a lithium battery. When the lithium battery runs out of power and is charged via a USB port, the chip will work under the USB power, which requires the chip to switch between two power supplies. Therefore, it is desirable to have a multi-input power supply solution.